1. Field of the Invention
The present invention relates to door opening/closing mechanisms for refrigerators and the like, and in particular to a door opening/closing mechanism for opening and closing the door from either the right-hand side or the left-hand side.
2. Description of Related Art
According to a prior art door opening/closing device as disclosed in, for example, Japanese Utility Model Publication No. HEI 5-5431, a door is provided with a securing plate having an engagement groove which can be releasably engaged with a hinge pin on a main body from the open side of the door, a latch plate which is releasably engaged in a pivotal manner with the hinge pin by a latch groove at both the right-hand and left-hand portions of the securing plate and constrains the hinge pin in the groove, and a connecting member on the door which is interlocked with the pivoting of the latch plate in a direction in which the constraint of the latch plate is released and prevents the other latch plate from pivoting.
As another prior art, Japanese Patent Laid-Open Publication No. 6-129759 discloses an automatic door opening/closing device with brake comprised of a motor with brake mounted so that its output shaft is disposed coaxially with the hinge pin of the door, a door opening/closing arm mounted to a lower end of the output shaft, an elastic member such as a spring and a resistance detector.
The former door opening/closing device is provided with a spring for constraining the pivoting of the latch plate. Therefore, a repelling force against the spring force is required in opening and closing the door, and this has the disadvantage that opening and closing the door require more force. There has been another problem that an operating noise (mechanical noise) is generated because the mechanism is operated against the spring force. Furthermore, if the latch plate on the open side is operated to be put into a locked state when the door is open, the door will be disengaged and fall off when a force is exerted on the pivot shaft side. In addition, due to an increased number of components, a complicated assembling work, high component and assembling costs and the components arranged all along the door, the device has had the problem that the whole mechanism occupies a large space.
On the other hand, since the driving of the pivoting operation is performed on the pivot shaft side in the latter door opening/closing device, a considerably great power is required as a load torque of the motor which serves as a driving power source. Furthermore, since the device is a single swing door system, there is the disadvantage that two drive power sources are required to cope with a double swing door system. Furthermore, in the case of the double swing door system, it is required to voluntarily switch the engagement between the drive unit and the door, and there is another problem that the door cannot be opened without electrification and cannot be opened from inside the refrigerator.